IM模块--UItextView带有placeholder属性，自动调节高度

╰半夏微凉° 2022-09-25 01:23 61阅读 0赞

参考资料：

\[简书地址\]([http://www.jianshu.com/users/23d0ae412e19/latest\_articles][http_www.jianshu.com_users_23d0ae412e19_latest_articles])

#import <UIKit/UIKit.h>
    
    @interface MessageInputView : UITextView
    
    
    @property (nonatomic,copy)  void (^UpdateTextFrame)(CGFloat th) ;
    
    
    
    @end

#import "MessageInputView.h"
    
    @interface MessageInputView()<UITextViewDelegate>
    
    @property (nonatomic,strong) UILabel *placeholderLabel;
    
    @end
    
    
    
    @implementation MessageInputView
    
    - (instancetype)initWithFrame:(CGRect)frame{
    
        self = [super initWithFrame:frame];
        if (self) {
            [self setUpUi];
        }
        return self;
    }
    
    
    - (void)setUpUi{
        _placeholderLabel = [[UILabel alloc]init];
        _placeholderLabel.font = [UIFont systemFontOfSize:15];
        _placeholderLabel.text = @"请输入";
        _placeholderLabel.textColor = [UIColor lightGrayColor];
        [self addSubview:_placeholderLabel];
        
        self.layer.cornerRadius = 6;
        self.layer.masksToBounds = YES;
        self.delegate = self;
        self.showsHorizontalScrollIndicator = NO;
        self.showsVerticalScrollIndicator = NO;
        self.scrollEnabled = NO;
        
        // 文本有改动的时候通知 ---
        [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(textViewChange) name:UITextViewTextDidChangeNotification object:nil];
    }
    
    
    - (void)layoutSubviews{
        [super layoutSubviews];
        
        _placeholderLabel.frame = CGRectMake(5, 0, self.bounds.size.width, self.bounds.size.height);
    }
    
    
    - (void)textViewChange{
        if (self.text.length == 0) {
            _placeholderLabel.hidden = NO;
        }else{
            _placeholderLabel.hidden = YES;
        }
    }
    
    
    
    #pragma mark   UITextViewDelegate  
    
    - (void)textViewDidChange:(UITextView *)textView{
        // 获取当前 TextView的高度
        CGFloat  tH = [textView sizeThatFits:textView.frame.size].height;
        NSLog(@"%f",tH);
        // 修改高度
        if (self.UpdateTextFrame != nil) {
            self.UpdateTextFrame(tH);
        }
    }
    
    
    
    @end

- (void)viewDidLoad {
        [super viewDidLoad];
        
        self.view.backgroundColor = [UIColor grayColor];
        MessageInputView  *messageView = [[MessageInputView alloc]initWithFrame:CGRectMake(50, 400, 100, 30)];
        
        __block MessageInputView *blockSelf = messageView;
        
        [messageView setUpdateTextFrame:^(CGFloat th) {
            [UIView animateWithDuration:0.2 animations:^{
                 blockSelf.frame = CGRectMake(50, 400, 100, th);
            }];
        }];
        
        [self.view addSubview:messageView];
        
    }

[http_www.jianshu.com_users_23d0ae412e19_latest_articles]: http://www.jianshu.com/users/23d0ae412e19/latest_articles